On Monday (Feb. 17),
Jimmy Fallon becomes the host of
"The Tonight Show" on NBC. He won the job largely on the basis of five strong years as the host of
"Late Night," where he showcased a great sense of fun, a willingness to try new things -- and get his guests to go along with them -- and a growing behind-the-desk presence.

In other words, he's come a long, long way than what you'll see in the video above -- Fallon's audition for
"Saturday Night Live" when he was a 23-year-old aspiring comic in 1998.

Spiky-haired and visibly nervous, Fallon runs through a series of impressions ranging from passable (
Jerry Seinfeld, Tommy Lee Jones) to very, very good (
Adam Sandler), a few original characters and a handful of musical bits. The latter are probably the best part of the audition, and you can see the seeds of some of his best "Late Night" musical moments there.

Unpolished as it looks now, the audition got him a job on "SNL" for the 1998-99 season, and the rest is TV history. Fallon's "Tonight Show" debut is set for midnight ET/PT Monday on NBC; he moves into his regular 11:35 p.m. home on Feb. 24 once NBC's Olympics coverage ends.